Batteries comprise one or more electrochemical cell, such cells generally comprising a cathode, an anode and an electrolyte. Lithium ion batteries are high energy density batteries that are fairly commonly used in consumer electronics and electric vehicles. In lithium ion batteries, lithium ions generally move from the negative electrode to the positive electrode during discharge and vice versa when charging. In the as-fabricated and discharged state, lithium ion batteries often comprise a lithium compound (such as a lithium metal oxide) at the cathode (positive electrode) and another material, generally carbon, at the anode (negative electrode).
The commercial importance of battery safety has recently become critically clear in the wake of many recent lithium ion battery fires and explosions. Commercial airline carriers, shippers, and others have taken to prohibiting the transport of certain lithium ion batteries and consumer electronics devices using lithium ion batteries. As year-over-year lithium ion battery capacity improvements have failed to keep up with demand, many battery companies have become aggressive in their attempts to improve capacity, sometimes at the expense of safety. For example, according to the New York Times, Samsung's recent difficulties with their consumer electronic lithium ion batteries have resulted from design flaws because of their “aggressive design decisions, which made problems more likely.” In particular, “[i]n the Note 7, Samsung opted for an exceptionally thin separator in its battery” in order to increase active material loading in the battery and, thereby, increase battery capacity. Because of the extremely thin nature of the separator, a much greater likelihood of failure was likely “if it breaks down, varies in thickness or is damaged by outside pressure.”